[嵌入式]RTT_0.96寸OLED_IIC驱动

1、前言

emm，这种应用跟rtt没多大关系，iic驱动也就是用到了其中的rt_i2c_transfer，不过还是写一下吧。

oled就是挺常见的，0.96寸，128*64的屏，用IIC接口驱动。

就算是从淘宝买的屏，商家也会有资料，各平台的例程，打开stm32的例程作为移植到现在代码的参考。

下面是如何向OLED写命令、写数据的代码、初始化OLED、某个位置显示字符串、显示整数、小数；

如果要画点、画线这样涉及到某个像素点的，还需要1M的缓存，[128][8]去保存当前屏幕的数据，更新这个数组然后再写。

2、铺路代码

2.1、向OLED写命令

//对OLED写某个命令cmd
static rt_err_t oled_write_cmd(uint8_t cmd)
{
    struct rt_i2c_msg msg;
    uint8_t buffer[2]={OLED_CMD_CMD,cmd};

    msg.addr = OLED_I2C_ADDR;
    msg.flags = RT_I2C_WR;
    msg.buf = buffer;
    msg.len = 2;

    if(rt_i2c_transfer(i2c_bus, &msg, 1) != 1){
        return RT_ERROR;
    }
    return RT_EOK;
}

2.2、向OLED写数据

//对OLED写数据data
static rt_err_t oled_write_data(uint8_t data)
{
    struct rt_i2c_msg msg;
    uint8_t buffer[2]={OLED_CMD_DATA,data};

    msg.addr = OLED_I2C_ADDR;
    msg.flags = RT_I2C_WR;
    msg.buf = buffer;
    msg.len = 2;

    if(rt_i2c_transfer(i2c_bus, &msg, 1) != 1){
        return RT_ERROR;
    }
    return RT_EOK;
}

2.3、设置OLED地址

//设置起始点坐标128*64
void oled_set_pos(uint8_t x,uint8_t y)
{
    oled_write_cmd(0xb0+y);
    oled_write_cmd(((x&0xf0)>>4)|0x10);
    oled_write_cmd((x&0x0f));
}

3、初始化OLED

• 首先要选择IIC，配置SCL和SDA的引脚，rt_device_find打开IIC设备。
• 根据卖家例程，上电需要延时、然后有一系列的命令、最后清屏。

//清屏
void oled_clear()
{
    uint8_t row,col;

    for(row = 0;row < 8;row++){
        oled_write_cmd(0xb0+row);       //page0-page1
        oled_write_cmd(0x00);           //low column start address
        oled_write_cmd(0x10);           //high column start address
        for(col=0;col<128;col++){
            oled_write_data(0x00);
        }
    }
}

//OLED初始化
void oled_init()
{
    rt_thread_mdelay(100);  //上电必须延时

    oled_write_cmd(0xAE); //display off
    oled_write_cmd(0x20); //Set Memory Addressing Mode
    oled_write_cmd(0x10); //00,Horizontal Addressing Mode;01,Vertical Addressing Mode;10,Page Addressing Mode (RESET);11,Invalid
    oled_write_cmd(0xb0); //Set Page Start Address for Page Addressing Mode,0-7
    oled_write_cmd(0xc8); //Set COM Output Scan Direction
    oled_write_cmd(0x00); //---set low column address
    oled_write_cmd(0x10); //---set high column address
    oled_write_cmd(0x40); //--set start line address
    oled_write_cmd(0x81); //--set contrast control register
    oled_write_cmd(0xff); //亮度调节 0x00~0xff
    oled_write_cmd(0xa1); //--set segment re-map 0 to 127
    oled_write_cmd(0xa6); //--set normal display
    oled_write_cmd(0xa8); //--set multiplex ratio(1 to 64)
    oled_write_cmd(0x3F); //
    oled_write_cmd(0xa4); //0xa4,Output follows RAM content;0xa5,Output ignores RAM content
    oled_write_cmd(0xd3); //-set display offset
    oled_write_cmd(0x00); //-not offset
    oled_write_cmd(0xd5); //--set display clock divide ratio/oscillator frequency
    oled_write_cmd(0xf0); //--set divide ratio
    oled_write_cmd(0xd9); //--set pre-charge period
    oled_write_cmd(0x22); //
    oled_write_cmd(0xda); //--set com pins hardware configuration
    oled_write_cmd(0x12);
    oled_write_cmd(0xdb); //--set vcomh
    oled_write_cmd(0x20); //0x20,0.77xVcc
    oled_write_cmd(0x8d); //--set DC-DC enable
    oled_write_cmd(0x14); //
    oled_write_cmd(0xaf); //--turn on oled panel

    oled_clear();           //清屏
}

rt_err_t oled_iic_startup()
{
    //查找I2C总线设备，获取I2C总线设备句柄
    i2c_bus = (struct rt_i2c_bus_device *)rt_device_find(OLED_I2C_BUS_NAME);
    if (i2c_bus == RT_NULL){
        LOG_D("can't find device!\n");
        return RT_ERROR;
    }

    //OLED初始化
    oled_init();

    return RT_EOK;
}

?

4、显示

4.1、字符串

//参数 : x,y：起始点坐标：(x:0~127, y:0~7);
//       ch[]：要显示的字符串;
//       TextSize：字符大小：(FONT_6x8代表6*8 ; FONT_8x16代表8*16)
void oled_show_string(uint8_t x, uint8_t y, uint8_t ch[], uint8_t TextSize)
{
    uint8_t c = 0,i = 0,j = 0;

    switch(TextSize){
        case FONT_6x8:{
            while(ch[j] != '\0'){   //循环到字符串末尾
                c = ch[j] - 32;
                if(x > 128-6){
                    x = 0; y++;     //当前行显示不完，自动转到下一行
                    if(y==8) break; //超出显示范围，退出
                }
                oled_set_pos(x,y);
                for(i=0;i<6;i++)    //显示一个字符
                    oled_write_data(F6x8[c][i]);
                x += 6;             //下一个位置
                j++;
            }
        }break;
        case FONT_8x16:{
            while(ch[j] != '\0'){
                c = ch[j] - 32;
                if(x > 128-8){
                    x = 0; y++;
                    if(y==7) break; //超出显示范围，退出
                }
                oled_set_pos(x,y);
                for(i=0;i<8;i++)    //显示一个字符
                    oled_write_data(F8X16[c*16+i]);
                oled_set_pos(x,y+1);
                for(i=0;i<8;i++)
                    oled_write_data(F8X16[c*16+i+8]);
                x += 8;
                j++;
            }
        }break;
    }
}

4.2、整数、小数（根据情况修改小数点后保留几位）

void oled_show_num(uint8_t x, uint8_t y, uint16_t num, uint8_t TextSize)
{
    uint8_t buffer[10];

    rt_snprintf(buffer,10,"%d",num);

    oled_show_string(x,y,buffer,TextSize);

}

void oled_show_double(uint8_t x, uint8_t y, double num, uint8_t TextSize)
{
    uint8_t buffer[20];

    rt_snprintf(buffer,20,"%f",num);

    oled_show_string(x,y,buffer,TextSize);

}

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